Open AccessCould the Galactic disc heating be due to globular cluster impacts?
Author(s) -
Vande Putte D.,
Cropper Mark,
Ferreras Ignacio
Publication year - 2009
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2009.15044.x
Subject(s) - globular cluster , physics , astrophysics , spiral galaxy , stars , cluster (spacecraft) , spiral (railway) , population , molecular cloud , horizontal branch , astronomy , mathematical analysis , demography , mathematics , sociology , computer science , programming language
So far, six mechanisms have been proposed to account for the Galactic disc heating. Of these, the most important appear to be a combination of scattering of stars by molecular clouds and by spiral arms. We study a further mechanism, namely the repeated disc impact of the original Galactic globular cluster population up to the present. We find that globular clusters could have contributed at most a small fraction of the current vertical energy of the disc, as they could heat the whole disc to σ z = 5.5 km s −1 (c.f. the observed 18 and 39 km s −1 for the thick and thin discs, respectively). We find that the rate of rise of disc heat ( α= 0.22 in σ z ∼ t α with t being time) is close to that found for scattering by molecular clouds.